JP6389856B2 - Ink composition and method for producing transparent conductor - Google Patents

Description

(Cross-reference to related applications)
This application claims the benefit of US Provisional Patent Application No. 61 / 295,634, filed January 15, 2010, under US Patent Act §119 (e). The entirety of this US provisional patent application 61 / 295,634 is incorporated herein by reference.

(background)
(Technical field)
The present disclosure relates to a low haze transparent conductor and an ink composition, and a method for producing them.

(Description of related technology)
The transparent conductor is an optically transparent conductive film. They are prevalent in areas such as displays, touch panels, photovoltaic (PV), various types of electronic paper, electrostatic shielding, heating or anti-reflective coatings (eg windows). Various technologies produce transparent conductors based on one or more conductive media such as metal nanostructures, transparent conductive oxides (eg, by sol-gel techniques), conductive polymers, and / or carbon nanotubes. To do. Generally, the transparent conductor further includes a transparent substrate on which a conductive film is deposited or coated.

  Depending on the end use, transparent conductors with predetermined electrical and optical properties can be created including, for example, sheet resistance, light transmission and haze. The production of transparent conductors often requires a balance between electrical performance and optical performance. For transparent conductors based on nanostructures, generally higher transmission and lower haze are typically associated with less conductive nanostructures, which are associated with higher sheet resistance (ie, lower conductivity). ).

  Many commercial applications of transparent conductors (eg touch panels and displays) need to maintain haze levels below 2%. Accordingly, the production of a low haze transparent conductor is particularly difficult because it may be impossible to maintain satisfactory conductivity in achieving such low levels of haze.

(Simple summary)
Low haze transparent conductor that maintains high electrical conductivity (eg, less than 350 ohms / square) while haze value is less than 1.5%, more typically less than 0.5%, and method of making the same Are described herein.

  One embodiment provides a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of less than 1.5% and a sheet resistance of less than 350 ohm / square. .

  A further embodiment provides a transparent conductor having a sheet resistance of less than 50 ohms / square.

  A further embodiment provides a transparent conductor having a haze value of less than 0.5%.

Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.3-0.4% and a sheet resistance of about 170-350 ohm / square. Is,
Provide a transparent conductor.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.4-0.5% and a sheet resistance of about 120-170 ohm / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.5-0.7% and a sheet resistance of about 80-120 ohm / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.7 to 1.0% and a sheet resistance of about 50 to 80 ohms / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 1.0-1.5% and a sheet resistance of about 30-50 ohm / square. A transparent conductor is provided.

A further embodiment is a transparent conductor of the above film specification, wherein more than 99% of the conductive nanostructures with an aspect ratio of at least 10 are less than 55 μm long or conductive with an aspect ratio of at least 10 More than 99% of the conductive nanostructures are 45 μm or less in length, or more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 50 μm in length, or the aspect ratio is at least More than 95% of the conductive nanostructures that are 10 are about 5 to 30 μm in length, or the average length of the conductive nanostructures that have an aspect ratio of at least 10 is about 10 to 22 μm, or A transparent conductor is provided wherein the conductive nanostructure having an aspect ratio of at least 10 has an average square length of about 120 to 400 μm ² .

  A further embodiment is a transparent conductor of the above film specification, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 55 nm or less, or have an aspect ratio of at least 10. More than 99% of the nanostructures have a diameter of 45 nm or less, or more than 95% of the conductive nanostructures having an aspect ratio of at least 10, or have an aspect ratio of at least 10 More than 95% of the conductive nanostructures are about 20 to 40 nm in diameter, or the average diameter of conductive nanostructures with an aspect ratio of at least 10 is about 26-32 nm with a standard deviation of 4-6 nm The average diameter of conductive nanostructures with a range or aspect ratio of at least 10 is about 29 nm with a standard deviation in the range of 4-5 nm Providing transparent conductor.

  A further embodiment is a transparent conductor of the above-mentioned film specification, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a length of 55 μm or less and the conductive nanostructures having an aspect ratio of at least 10 More than 99% of the structures have a diameter of 55 nm or less, or more than 95% of the conductive nanostructures with an aspect ratio of at least 10 have a length of about 5 to 50 μm and have an aspect ratio of at least 10 More than 95% of the nanostructures are about 15 to 50 nm in diameter, or more than 95% of the conductive nanostructures with an aspect ratio of at least 10 are about 5 to 30 μm in length, and the aspect ratio is at least 10. More than 95% of certain conductive nanostructures are about 20 to 40 nm in diameter, or the average length of conductive nanostructures having an aspect ratio of at least 10 is about 1 The conductive nanostructures having an aspect ratio of at least 10 and having an average diameter of about 26 to 32 nm and a standard deviation in the range of 4 to 6 nm, or an aspect ratio of at least 10 Provided is a transparent conductor in which more than 99% of the conductive nanostructures have a length of 45 μm or less and more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 45 nm or less.

A further embodiment is a method comprising growing metal nanowires from a reaction solution comprising a metal salt and a reducing agent, the growing step comprising:
Reacting the metal salt in the reaction solution with the first portion of the reducing agent for a first time, and maintaining a substantially constant concentration of less than 0.1% w / w of the metal salt in the reaction solution A method is provided that includes gradually adding a second portion of salt over a second time period.

  A further embodiment includes a plurality of conductive nanostructures having a length of 55 μm or less, greater than 99% of the conductive nanostructures having an aspect ratio of at least 10, a viscosity modifier, a surfactant, and a dispersion An ink composition comprising a fluid is provided.

Additional embodiments include that greater than 99% of the conductive nanostructures having an aspect ratio of at least 10 are 45 μm or less in length, or greater than 95% of the conductive nanostructures having an aspect ratio of at least 10 Conductive nanostructures having a length of about 5 to 50 μm, or greater than 95% of conductive nanostructures having an aspect ratio of at least 10 or having an aspect ratio of at least 10 The ink composition has an average length of about 10 to 22 μm, or a conductive nanostructure having an aspect ratio of at least 10 and an average square length of about 120 to 400 μm ² .

  A further embodiment includes a plurality of conductive nanostructures having a diameter of 55 nm or less, greater than 99% of the conductive nanostructures having an aspect ratio of at least 10, a viscosity modifier, a surfactant, and a dispersion fluid An ink composition is provided.

  Additional embodiments include that greater than 99% of the conductive nanostructures having an aspect ratio of at least 10 are 45 nm or less in diameter and greater than 95% of the conductive nanostructures having an aspect ratio of at least 10 are from about 15 in diameter. More than 95% of the conductive nanostructures with an aspect ratio of at least 10 have a diameter of about 20 to 40 nm and the average diameter of the conductive nanostructures with an aspect ratio of at least 10 has an average diameter of about 26 to 32 nm. An ink composition is provided wherein the standard deviation is in the range of 4-6 nm, the average diameter of the conductive nanostructure having an aspect ratio of at least 10 is about 29 nm, and the standard deviation is in the range of 4-5 nm To do.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, the composition comprising a plurality of conductive nanostructures, a viscosity modifier, a surfactant, and a dispersion fluid. Inclusive, more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a length of 55 μm or less, and more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 55 nm or less A composition is provided.

  An additional embodiment is that more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 50 μm in length, and more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are in diameter. More than 95% of the conductive nanostructures having a length of about 5 to 30 μm and an aspect ratio of at least 10 are about 95% of the conductive nanostructures that are about 15 to 50 nm or have an aspect ratio of at least 10 Conductive nanostructures having an average length of about 10-22 μm and an aspect ratio of at least 10 for conductive nanostructures having an ultra length of about 20-40 nm or an aspect ratio of at least 10 9 of conductive nanostructures having an average body diameter of about 26-32 nm and a standard deviation in the range of 4-6 nm, or an aspect ratio of at least 10. Percent is at 45μm or less in length, 99% of the aspect ratio of at least 10 conductive nanostructures is less than the diameter 45 nm, to provide an ink composition.

(Brief explanation of several ways of viewing the drawings)
In the drawings, identical reference numbers indicate similar elements or acts. The sizes and relative positions of elements in the figures are not necessarily drawn to scale. For example, the shapes and angles of the various elements are not drawn to scale, and some of these elements are arbitrarily enlarged and arranged for ease of reading the figure. Further, the particular shape of the depicted element is not intended to convey any information regarding the actual shape of the particular element, but is selected merely to facilitate reading in the figures.

FIG. 1 is a histogram showing a distribution profile of a population of nanowires by length. FIG. 2 is a histogram showing the distribution profile of the nanowire population by diameter. FIG. 3 is a flow chart of a two-step reaction scheme for preparing silver nanowires according to a certain size distribution profile. FIG. 4 shows the effect of purification on the diameter distribution of silver nanowires prepared by a two-step reaction. FIG. 5 shows the length distribution profile of three batches of silver nanowires as a lognormal distribution. FIG. 6 shows the diameter distribution profile of three batches of silver nanowires as a normal distribution, ie a Gaussian distribution. FIG. 7 shows an inverse correlation between haze and resistance of a conductive thin film formed of silver nanowires. FIG. 8 shows a positive correlation between transmittance and resistance of a conductive thin film formed of silver nanowires.

(Detailed description of the invention)
In general, the transparent conductors described herein are conductive thin films of conductive nanostructures. In transparent conductors, one or more conductive paths are established by continuous physical contact between nanostructures. A conductive network of nanostructures is formed when there are enough nanostructures to reach the electrical percolation threshold. Therefore, the electrical percolation threshold is an important value, and long-distance connectivity exceeding that value can be obtained.

The conductivity of a conductive film is often measured by “film resistance”, “resistivity” or “sheet resistance” and is expressed in ohm / square (or “Ω / □”). Film resistance is at least a function of surface packing density, nanostructure size / shape, and electrical properties inherent in the nanostructure components. As used herein, a thin film is considered conductive when it has a sheet resistance of 10 ⁸ Ω / □ or less. Preferably, the sheet resistance is 10 ⁴ Ω / □, 3,000 Ω / □, 1,000 Ω / □, or 350 Ω / □, or 100 Ω / □ or less. Typically, the sheet resistance of a conductive network formed of metal nanostructures is 10Ω / □ to 1000Ω / □, 100Ω / □ to 750Ω / □, 50Ω / □ to 200Ω / □, 100Ω / □ to 500Ω. / □, or 100Ω / □ to 250Ω / □, or 10Ω / □ to 200Ω / □, 10Ω / □ to 50Ω / □, or 1Ω / □ to 10Ω / □.

  Optically, transparent conductors based on nanostructures have a high light transmission in the visible region (400-700 nm). Typically, a transparent conductor is considered optically transparent when the light transmission exceeds 85% in the visible region. More typically, the light transmission is greater than 90%, or greater than 93%, or greater than 95%.

  Haze is another indicator of optical transparency. It is generally recognized that haze is due to light scattering and reflection / refraction due to both bulk and surface roughness effects. Low haze transparent conductors are particularly desirable for applications such as touch screens and displays where optical transparency is one of the important performance factors.

  When the nanostructure is a transparent conductor forming a conductive medium, light scattering caused by the nanostructure is inevitable. However, as described herein, low haze transparent conductors can be obtained by controlling the size distribution profile and particle morphology of the nanostructures.

  In general, the level at which haze can be detected by the human eye is about 2%. Accordingly, various embodiments of the present disclosure are directed to transparent conductors having a haze of less than 1.5%.

  One embodiment provides a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of less than 1.5% and a sheet resistance of less than 350 ohm / square. .

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze value of less than 1.5% and a sheet resistance of less than 50 ohms / square. provide.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze value of less than 0.5% and a sheet resistance of less than 350 ohms / square. provide.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze value of less than 0.3% and a sheet resistance of less than 350 ohm / square. provide.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.3-0.4% and a sheet resistance of about 170-350 ohm / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.4-0.5% and a sheet resistance of about 120-170 ohm / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.5-0.7% and a sheet resistance of about 80-120 ohm / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 0.7 to 1.0% and a sheet resistance of about 50 to 80 ohms / square. A transparent conductor is provided.

  Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze of about 1.0-1.5% and a sheet resistance of about 30-50 ohm / square. A transparent conductor is provided.

Nanostructure Size Distribution Profile In order to meet the above thin film specifications including transmittance, sheet resistance and haze, the transparent conductor includes nanostructures that follow a certain size distribution profile.

  As used herein, a “conductive nanostructure” or “nanostructure” generally has at least one dimension (ie, width) of less than 500 nm, more typically less than 100 nm or 50 nm, and even more typically 20 Refers to a conductive nano-sized structure in the range of 40 nm to 40 nm. In the longitudinal direction, the nanostructures are over 500 nm in length, over 1 μm, or over 10 μm. More typically, nanostructures range in length from 5 to 30 μm.

  The nanostructure can be in any shape or geometric form. One way to define the geometry of a given nanostructure is by its “aspect ratio”, which refers to the ratio of the length and width (or diameter) of the nanostructure. In some embodiments, the nanostructure is an isotropic shape (ie, aspect ratio = 1). Exemplary isotropic or substantially isotropic nanostructures include nanoparticles. In a preferred embodiment, the nanostructure is an anisotropic shape (ie, aspect ratio ≠ 1). Anisotropic nanostructures typically have a long axis along their length. Exemplary anisotropic nanostructures include nanowires (solid nanostructures with an aspect ratio of at least 10, more typically at least 50), nanorods (solid nanostructures with an aspect ratio of less than 10), and nanotubes (hollow Nanostructures).

  In addition to the packing density of nanostructures, their size and shape are also factors that determine membrane specifications. More specifically, the length, width and aspect ratio of the nanostructures often affect the final sheet resistance (R), transmittance (T) and haze (H) to different degrees. For example, the length of the nanostructure typically affects the degree of interconnectivity of the nanostructure and then affects the sheet resistance of the transparent conductor. The width of the nanostructure usually does not affect the interconnectivity of the nanostructure, but can significantly affect the haze of the transparent conductor.

  In practice, a given population of nanostructures (eg, products after synthesis and purification) will contain a range of sizes (lengths and widths) of nanostructures rather than uniform sizes. Accordingly, the specifications (R, T, and H) of the thin film formed by such a nanostructure population depend on the collective contribution of the nanostructure over the size distribution profile.

  The size distribution profile includes a set of values that define the relative amount or frequency of nanostructures present, sorted according to their size (length and width).

  The size distribution profile can be displayed graphically with a histogram. A histogram is created by sorting a given population of nanostructures according to non-overlapping regular intervals of a size range and plotting the frequency of nanostructures falling into each interval. The regular spacing of the size range is also referred to as “range range”.

  FIG. 1 is a histogram showing a distribution profile of a group of nanostructures (for example, nanowires) according to their length, where the X-axis is a range (5 μm interval) and the Y-axis is a frequency shown in a columnar shape. A smooth curve can also be drawn based on the probability density function, taking into account the length and corresponding frequency data. Therefore, FIG. 1 quantitatively shows the shape (log normal distribution) and spread (variation before and after the average) of the length distribution in the population of nanostructures in a graph.

  In addition, FIG. 1 shows the maximum and minimum lengths of the length range. Certain nanostructures that do not contribute to conductivity and contribute to light scattering are present much less frequently in the size distribution profile (eg, less than 10%, or more typically less than 5%) Can be recognized. These nanostructures are seen as “bright objects” due to their appearance on dark field micrographs. These bright objects include, for example, nanostructures (eg, nanoparticles, nanorods) that are too wide and / or too short to effectively participate in the electrical percolation process. Some or all of these bright objects have a low aspect ratio (less than 10).

  Accordingly, one embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures, having a haze of less than 1.5% and a sheet resistance of less than 350 ohm / square, wherein the aspect ratio A low haze transparent conductor is provided in which more than 99% of the conductive nanostructures having a length of at least 10 are 55 μm or less.

  A further embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures and having a haze value of less than 1.5%, the conductive nanostructure having an aspect ratio of at least 10. Provided is a low haze transparent conductor having a length of more than 99% of 45 μm or less.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are long. A transparent conductor is provided which is about 5 to 50 μm.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are long. A transparent conductor is provided that is about 5 to 30 μm.

In addition to the length distribution, the average length (<l>) and average square length (<l ² >) of the nanostructures also indicate the membrane specification. In particular, the average square length of the nanostructure (<l ² >) determines the percolation threshold and is therefore directly related to the sheet resistance. Co-owned copending US patent application Ser. No. 11 / 871,053 provides a more detailed analysis of the correlation between these two parameters and the sheet resistance of transparent conductors based on nanowires. This application is incorporated herein by reference in its entirety.

  As used herein, the average length (<l>) is the sum of all measured lengths divided by the nanostructure count, as described herein.

The average square length (<l ² >) is

で表すことができる。

Can be expressed as

  Accordingly, a further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, the average length of the conductive nanostructures having an aspect ratio of at least 10 Provides a transparent conductor having a thickness of about 10-22 μm.

  In various further embodiments, the average length of conductive nanostructures having an aspect ratio of at least 10 is about 12-20 μm, 14-18 μm, or 15-17 μm.

Another embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein the mean square length of the conductive nanostructures having an aspect ratio of at least 10 A transparent conductor is provided that is about 120-600 μm ² .

In various further embodiments, the average square length of conductive nanowires having an aspect ratio of at least 10 is about 240-400 μm ² or 260-350 μm ² .

  FIG. 2 is a histogram showing a distribution profile of a group of nanostructures (for example, nanowires) by diameter, the X-axis is a range (5 nm interval), and the Y-axis is a columnar frequency. A smooth curve can also be drawn based on the probability density function, taking into account the diameter and corresponding frequency data. Therefore, FIG. 2 quantitatively shows the shape (normal, ie, Gaussian distribution) and spread (variation before and after the average) of the diameter distribution in the body population of nanostructures.

  As a result of the normal distribution, the distribution profile of the plurality of nanostructures can be defined by the mean diameter and standard deviation.

  FIG. 2 shows a narrow distribution of nanostructure diameters (ie, a relatively small standard deviation). As used herein, a normal distribution is considered narrow when the standard deviation is less than 20% of the average, or more typically less than 15% of the average. The narrow diameter distribution is believed to suppress compositional non-uniformity of the membrane nanostructure and result in low haze.

  Accordingly, one embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 Provide a transparent conductor that is 55 nm or less.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 Provide a transparent conductor that is 45 nm or less.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 A transparent conductor is provided that is about 15 to 50 nm.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 A transparent conductor is provided that is about 20 to 40 nm.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein the average diameter of the conductive nanostructures having an aspect ratio of at least 10 is about 26. A transparent conductor with a standard deviation in the range of 4 to 6 nm is provided.

  A further embodiment is a transparent conductor comprising a plurality of conductive nanostructures having a haze value of less than 1.5%, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 29 nm. And providing a transparent conductor with a standard deviation in the range of 4-5 nm.

  A further embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures and having a haze value of less than 1.5%, the conductive nanostructure having an aspect ratio of at least 10. Provided is a low haze transparent conductor in which more than 99% has a length of 55 μm or less, and more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 55 nm or less.

  A further embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures and having a haze value of less than 1.5%, the conductive nanostructure having an aspect ratio of at least 10. Provided is a low haze transparent conductor in which more than 99% of the conductive nanostructures having a length of 45 μm or less and an aspect ratio of at least 10 have a diameter of more than 99% of 45 nm or less.

  A further embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures and having a haze value of less than 1.5%, the conductive nanostructure having an aspect ratio of at least 10. A low haze transparent conductor is provided wherein greater than 95% of the conductive nanostructures having a length of about 5 to 50 μm and an aspect ratio of at least 10 are greater than 95% are about 15 to 50 nm in diameter.

  A further embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures and having a haze value of less than 1.5%, the conductive nanostructure having an aspect ratio of at least 10. A low haze transparent conductor is provided wherein greater than 95% is about 5 to 30 μm in length and greater than 95% of the conductive nanostructures having an aspect ratio of at least 10 is about 20 to 40 nm in length.

  A further embodiment is a low haze transparent conductor comprising a plurality of conductive nanostructures and having a haze value of less than 1.5%, the conductive nanostructure having an aspect ratio of at least 10. A low haze value having an average length of about 10-22 μm, and an average diameter of conductive nanostructures having an aspect ratio of at least 10 of about 26-32 nm and a standard deviation in the range of 4-6 nm Provide a transparent conductor.

  Additional embodiments provide that the haze of any of the low haze transparent conductors is less than 1.0%, less than 0.8%, or less than 0.6%, or less than 0.5%, or 0.4% Less than or less than 0.3%.

  In an additional embodiment, in any of the low cloudiness transparent conductors, the conductive nanostructure having an aspect ratio of at least 10 includes nanowires (including but not limited to metal nanowires (eg, silver nanowires)). And metal nanotubes (eg, silver or gold nanotubes).

Nanostructure Preparation Nanostructures (eg, metal nanowires) that follow the size distribution profiles described herein can be prepared by chemical synthesis.

  Conventionally, metal nanowires can be nucleated and grown from a solution of the corresponding metal salt in the presence of an excess of a reducing agent that also serves as a solvent (eg, ethylene glycol or propylene glycol). In this type of solution phase reaction, nanowire growth typically proceeds simultaneously in the radial and axial directions. Thus, the diameter increases as the nanowire stretches. For example, Y. Sun, B.D. Gates, B.B. Mayers, & Y. See Xia, “Crystalline silverware by soft solution processing”, Nanolett, (2002), 2 (2): 165-168.

  For the low haze transparent conductors described herein, the nanowires can have a relatively small diameter (eg, an average diameter of 15-50 nm) and a narrow width distribution. In these diameter ranges, conventional synthesis produces nanowires that are much shorter than the length distribution (including the average length) that gives good conductivity (eg, less than 350 ohms / square). Conversely, if the nanowire grows to the length necessary to reach good conductivity, the nanowire diameter should be large enough to increase the haze (eg, greater than 1.5%). Is inevitable.

  A two-step synthesis is described to provide a population of nanowires that follow a size distribution profile and thereby form a low cloudiness transparent conductive film.

  Two-step synthesis promotes the radial and axial growth of the nanowires separately, so that the diameter and length of the nanowires can be controlled separately. FIG. 3 is a flow chart showing the two-step preparation of silver nanowires that nucleate and grow from a propylene glycol solution of silver nitrate. Additional components of the reaction include polyvinyl pyrrolidone and tetra-n-butylammonium chloride (TBAC). By controlling the amount and order of silver nitrate addition, the nanowire growth and final size can be controlled.

  The silver nitrate solution contains a predetermined total amount of silver nitrate and is divided into two parts that are added at two different stages of the reaction. The division can be in the range of 30-70: 70-30, preferably 50:50.

  In the first stage of the reaction, a first portion of total silver nitrate is used. In addition, a portion of the first portion of silver nitrate is introduced with the TBAC. As a result, the initial silver ion concentration of the reaction mixture is about 0.001 to 0.025%. Thereafter, the remainder of the first portion of silver nitrate is added. The first stage of the reaction is typically carried out for 12-16 hours. During this stage, nanowires are grown and formed both radially and axially. At the end of the first stage, the length of the nanowire is shorter than the final desired length, but the nanowire diameter is much closer to its final dimension.

  In the second stage of the reaction, a second portion of silver nitrate is gradually added over a period of time, during which the concentration of silver ions in the reaction solution is approximately constant and less than 0.1% w / w. During the second phase, the main wire growth is axial, while the radial growth is effectively slowed down or even stopped.

  The total reaction time for the two stages is about 24 hours. The reaction can be quenched with deionized (DI) water, at which point growth in all directions stops.

  Throughout the reaction, the reaction mixture is preferably maintained in an inert atmosphere. The inert gas may be a noble gas (eg, helium, neon, argon, krypton or xenon), or other inert gas such as nitrogen, or an inert gas mixture, or a composite gas. Typically, the reactor is first purged with an inert gas for a predetermined time. Purging continues throughout the reaction. A more detailed description of purging can be found in co-pending and co-owned US patent application 61 / 275,093, which is hereby incorporated by reference in its entirety.

Accordingly, one embodiment is a method comprising growing metal nanowires from a reaction solution comprising a metal salt and a reducing agent, the growing step comprising:
Reacting the metal salt in the reaction solution with the first portion of the reducing agent for a first time, and maintaining a substantially constant concentration of less than 0.1% w / w of the metal salt in the reaction solution A method is provided that includes gradually adding a second portion of salt over a second time period.

  A further embodiment provides that the metal nanowire is a silver nanowire, the metal salt is silver nitrate, and the reducing agent is propylene glycol or ethylene glycol.

  A further embodiment provides that the first and second portions of the metal salt are approximately equal.

Another embodiment is that during the first time, a portion of the first portion of the metal salt is an ammonium salt (T
BAC) is added first, followed by the remainder of the first portion of the metal salt. In some embodiments, the portion is about 0.6% of the total metal salt and about 0.001 to 0.025% w / w of metal ions in the reaction mixture.

  Although nanowires (eg, silver nanowires) have been described in connection with the above two-step synthesis, it should be understood that nanowires of other conductive materials can be similarly prepared. Another metallic material can be an elemental metal (eg, a transition metal) or a metal compound (eg, a metal oxide). The metal material may be a bimetal material or metal alloy containing two or more kinds of metals. Suitable metals include, but are not limited to, silver, gold, copper, nickel, gold plated silver, platinum and palladium.

Thin Film Preparation In various embodiments, the transparent conductor described herein is a thin film formed from a dispersion of nanostructures, also referred to as an “ink composition”.

A typical ink composition for depositing metal nanowires is 0.0025% to 0.1% surfactant by weight (eg, the preferred range is 0.0025 for Zonyl® FSO-100). % To 0.05%, or 0.005% to 0.025% Triton X-100), viscosity modifier 0.02% to 4% (for example, the preferred range is hydroxypropyl methylcellulose (HPMC) From 0.02% to 0.5%)
0.01 to 1.5% metal nanowires and 94.5% to 99.0% fluid (dispersing or suspending other components).

  In various embodiments, the silver nanowire ink composition comprises 0.1% to 0.2% silver nanowires, 0.2 to 0.4% high purity HPMC, and 0.005% to 0.025. % Triton X-100. Methods for purifying HPMC are described in co-pending and co-owned US patent application 61 / 175,745, which is hereby incorporated by reference in its entirety.

  Representative examples of suitable surfactants include ZONYL (R) FSN, ZONYL (R) FSO, ZONYL (R) FSA, ZONYL (R) FSH (DuPont Chemicals, Wilmington, DE). (Registered trademark) surfactants, and fluorine-based surfactants such as NOVEC ™ (3M, St. Paul, MN). Another exemplary surfactant includes alkylphenol ethoxylate-based nonionic surfactants. Preferred surfactants include, for example, octylphenol ethoxylates such as TRITON ™ (x100, x114, x45), and nonylphenol ethoxylates such as TERGITOL ™ (Dow Chemical Company, Midland MI). Further exemplary nonionic surfactants include acetylenic surfactants such as DYNOL® (604, 607) (Air Products and Chemicals, Inc., Allentown, Pa.), And n-dodecyl β- D-maltoside is mentioned.

  Examples of suitable viscosity modifiers include hydroxypropyl methylcellulose (HPMC), methylcellulose, xanthan gum, polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose. Examples of suitable fluids include water and isopropanol.

  Accordingly, one embodiment provides an ink composition comprising a plurality of conductive nanostructures, wherein more than 99% of the conductive nanostructures are 55 μm or less in length.

  A further embodiment provides an ink composition comprising a plurality of conductive nanostructures, wherein more than 99% of the conductive nanostructures are 45 μm or less in length.

  A further embodiment provides an ink composition comprising a plurality of conductive nanostructures, wherein more than 95% of the conductive nanostructures are about 5 to 50 μm in length.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 30 μm in length A composition is provided.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein the average length of conductive nanostructures having an aspect ratio of at least 10 is about 10-22 μm. I will provide a.

Another embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein the average square length of the conductive nanostructures having an aspect ratio of at least 10 is about 120-400 μm ^2. A composition is provided.

  Another embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 55 nm or less. provide.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 are 45 nm or less in diameter. provide.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of about 15 to 50 nm. Offer things.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 20 to 40 nm in diameter. Offer things.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein the conductive nanostructures having an aspect ratio of at least 10 have an average diameter of about 26-32 nm and a standard deviation of 4 An ink composition is provided that is in the range of -6 nm.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein the conductive nanostructures having an aspect ratio of at least 10 have an average diameter of about 29 nm and a standard deviation of 4-5 nm. Ink compositions that are in the range are provided.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 are 55 μm or less in length and the aspect ratio is An ink composition is provided wherein greater than 99% of the conductive nanostructures that are at least 10 have a diameter of 55 nm or less.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 are 45 μm or less in length and the aspect ratio is An ink composition is provided wherein greater than 99% of the conductive nanostructures that are at least 10 are 45 nm in diameter or less.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 50 μm in length, An ink composition is provided wherein greater than 95% of the conductive nanostructures having a ratio of at least 10 are about 15 to 50 nm in diameter.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 30 μm in length, An ink composition is provided wherein greater than 95% of the conductive nanostructures having a ratio of at least 10 are about 20 to 40 nm in length.

  A further embodiment is an ink composition comprising a plurality of conductive nanostructures, wherein the average length of conductive nanostructures having an aspect ratio of at least 10 is about 10-22 μm, and the aspect An ink composition is provided wherein the conductive nanostructures having a ratio of at least 10 have an average diameter of about 26-32 nm and a standard deviation in the range of 4-6 nm.

  Further embodiments define in each of the above embodiments that the nanostructure is a metal nanowire (eg, a silver nanowire).

  The ink composition can be prepared based on the desired concentration of total nanostructures (eg, nanowires), which is an indicator of the packing density of the final conductive film formed on the substrate.

  The substrate can be any material on which the nanowires are deposited. The substrate may be rigid or flexible. Preferably, the substrate is also optically transparent, i.e. the light transmittance of the material is at least 80% in the visible region (400 nm to 700 nm).

  Examples of rigid substrates include glass, polycarbonate, acrylic and the like. In particular, special glasses such as glass containing no alkali (for example, borosilicate), low alkali glass, and zero-expansion glass-ceramic can be used. Special glass is particularly suitable for thin panel display systems including liquid crystal displays (LCDs).

  Examples of flexible substrates include polyesters (eg, polyethylene terephthalate (PET), polyester naphthalates and polycarbonates), polyolefins (eg, linear, branched and cyclic polyolefins), polyvinyls (eg, polyvinyl chloride). , Polyvinylidene chloride, polyvinyl acetal, polystyrene, polyacrylate, etc.), cellulose ester bases (eg, cellulose triacetate, cellulose acetate), polysulfones such as polyethersulfone, polyimides, silicones and other conventional polymer membranes But is not limited to that.

  The ink composition can be deposited on a substrate, for example, by the method described in co-pending US patent application Ser. No. 11 / 504,822.

  Spin coating is a typical technique for depositing a uniform film on a substrate. By controlling the filling amount, rotation speed and time, thin films having various thicknesses can be formed. It will be appreciated that the viscosity and shear behavior of the suspending fluid, as well as the interactions between the nanowires, can affect the distribution and interconnectivity of the deposited nanowires.

  For example, the ink composition described herein can be spin coated onto a glass substrate at a speed of 400-2000 rpm for 60 seconds at an acceleration of 1000 rpm / s. The thin film can be further subjected to some post-treatment, including baking at 50 ° C. for 90 seconds and 140 ° C. for 90 seconds. Further, pressure treatment with or without heating can be further utilized to adjust the final membrane specification.

  As will be appreciated by those skilled in the art, other deposition techniques such as sedimentation flow metered by narrow channels, die flow, flow over gradients, slit coating, gravure coating, micro gravure coating, bead coating, dip coating Slot die coating, etc. can be used. Printing techniques can be used to print the ink composition directly on the substrate, with or without a pattern. For example, ink jet, flexographic printing and screen printing can be used.

Nanowire sizing The length and width of nanostructures (eg, nanowires) and their numbers are measured by a combination of microscopy and software-assisted image analysis (eg, available from Cremex Technologies Inc (Quebec, Canada)) Can count. Regardless of the technique used for measurement and counting, microscope systems, including optics, cameras, and image analysis software, are validated and / or regularly spaced using National Institutes Standards and Technology (NIST) traceable standards. Or it should be calibrated.

  A magnified image of the nanowire can be measured using an optical microscope (eg, Olympus BX51) equipped with a high resolution digital camera, Cremex stage, and Cremex analysis software.

  Microscope illumination clearly illuminates each nanostructure to enhance the contrast of the nanostructure against the background so that the image analysis software can accurately recognize and measure the nanostructure Should be adjusted to. For example, the microscope can be set to dark field and focus on the image on the monitor at 500x magnification. Each frame on the monitor can be set to represent a 258 μm × 193 μm area on the membrane.

  The wire density should be such that the majority of the wires are separated from each other and do not overlap. If there are 25 or fewer (or more typically 40 or fewer) wires per frame, overlap can be managed or minimized. In order to reduce the incidence of overlapped wires, the initial dilution dispersion of nanowires can be further diluted. If the density of the wire is too low (less than 5 per frame), the nanowire concentration of the starting nanowire dispersion should be increased. Nanowires that touch or are cut at the edge of the image are automatically excluded from the measurement using image analysis software. In addition, bright objects, such as nanostructures with an aspect ratio of less than 10, are excluded from measurement and counting.

  For example, to measure the length of a population of nanowires, an initial diluted dispersion of metal nanowires (about 0.001 wt% metal) in isopropanol is spin coated onto a 2 inch x 2 inch piece of clean glass at 1000 rpm for 30 seconds. be able to. The membrane is then dried.

  The length of the nanowire can be measured by initiating a special routine or program using the Cremex software.

プログラムが１４４フレームを通過すると長さが自動的に測定される。測定終了後、Ｃｌｅｍｅｘソフトウェアは、（平均長さ、標準偏差、平均平方長さ、及び値域ごとにまとめられた長さ分布を含めて）重要なデータすべてを含む統計学的報告書を作成する。結果を受け取るためには、総ワイヤ計数は８００〜６０００ワイヤとすべきである。ワイヤ計数がこの範囲外である場合、初期ナノワイヤ分散系を希釈調節して試験を繰り返さなければならない。本明細書で考察したように、明るい物体、例えば、アスペクト比１０未満のナノ構造体は、計数から除外される。

The length is automatically measured as the program passes 144 frames. After the measurement is complete, the Cremex software generates a statistical report that includes all the important data (including the average length, standard deviation, average square length, and length distribution organized by range). To receive results, the total wire count should be between 800 and 6000 wires. If the wire count is outside this range, the test must be repeated with the initial nanowire dispersion diluted. As discussed herein, bright objects, such as nanostructures with an aspect ratio of less than 10, are excluded from counting.

  The width of the nanowire is measured by a scanning electron microscope (SEM).

  To prepare the sample, a few drops (about 0.05 wt% metal) of the diluted nanowire dispersion in methanol are added to the clean aluminum SEM sample stage. The methanol is dried and the sample is rinsed several times with additional amounts of methanol to remove organic residues from the nanowires. Samples are dried and then inserted into an SEM instrument (eg, a Hitachi S-4700 SEM that has been verified and / or calibrated at regular intervals using NIST traceable standards).

  The SEM beam acceleration voltage is set to about 10.0 kV. Typically, 8 or more SEM photographs from 60K to 80K are taken. Sufficient photos should be taken to measure at least 150 wires (typically 6-10 photos).

  For accurate measurement and analysis, the nanowires should be separated from each other in a thin layer and free of organic residues. Furthermore, the image should be well focused.

  After the SEM image is obtained, the photo is uploaded to the Cremex Image Analysis software programmed with a special analysis routine.

幅を測定するために、画像中のナノワイヤすべての輪郭をまず自動的に強調する。使用者は、各画像の相対グレー閾値を手作業で調節して、ナノワイヤが分析前に正確に強調されるのを確実にすることができる。使用者は、測定すべき個々のワイヤを選択し、標識することもできる。次いで、Ｃｌｅｍｅｘソフトウェア（又は別の適切なソフトウェアツール）は、全分析データを収集し、（平均直径及び標準偏差、平均平方直径、並びに値域ごとにまとめられた直径分布を含めて）重要なデータすべてを含む統計学的報告書を作成する。

To measure the width, the outline of all nanowires in the image is first automatically enhanced. The user can manually adjust the relative gray threshold of each image to ensure that the nanowire is accurately highlighted before analysis. The user can also select and label individual wires to be measured. The Cremex software (or another appropriate software tool) then collects all the analytical data, including all important data (including mean diameter and standard deviation, mean square diameter, and diameter distribution organized by range). Create a statistical report that includes

  Various embodiments described herein are further illustrated by the following non-limiting examples.

Example 1
Multi-step synthesis of silver nanowires Silver nanowires according to a certain size distribution profile were synthesized in a two-step process.

An AgNO ₃ solution was first prepared by mixing 6 grams of silver nitrate (AgNO ₃ ) with 37 grams of propylene glycol (14% w / w).

  445 grams of propylene glycol and 7.2 grams of polyvinyl pyrrolidone were added to the reactor and then heated to 90 ° C. After the mixture in the reactor has stabilized at 90 ° C., the atmosphere in the reactor headspace is purged with nitrogen for at least 5 minutes before silver nitrate is added.

  In the first stage of the reaction, half of the total silver nitrate was used. Accordingly, 0.6% silver nitrate solution and 1.18 grams of tetra-n-butylammonium chloride hydrate in propylene glycol (10% solution) were sequentially added to the heated reactor, followed by 49.4 silver nitrate solution. % Was added. The reaction was carried out for 12-16 hours.

  In the second stage of the reaction, axial growth was dominant, while radial growth was effectively inhibited. The remaining 50% of the silver nitrate solution was gradually added while maintaining an approximately constant concentration of silver ions (over 8 hours). The reaction was run for a total of up to 24 hours, during which time a nitrogen purge was continued. At the end of the reaction, the reaction mixture was quenched with 100 grams of deionized (DI) water.

  The reaction can be carried out in ambient light (standard) or in the dark that minimizes light-induced degradation of the resulting silver nanowires.

(Example 2)
Purification of silver nanowires The crude product of Example 1 contained a crude liquid (eg, reaction solvent, DI water, reaction by-products) and the resulting nanowires. A small amount of nanoparticles and nanorods were also present.

  The crude product was collected in a closed sedimentation vessel and allowed to settle for 4 to 20 days. After sedimentation, the crude product was separated into supernatant and sediment. The sediment mainly contained silver nanowires and the crude liquid, nanorods and nanoparticles remained in the supernatant.

  The supernatant was removed and the sediment was resuspended in DI water and rocked on a rocking table to facilitate mixing. Pipetting was repeated for final resuspension.

  FIG. 4 shows the effect of purification on the diameter distribution. Both crude and purified nanowires follow a substantially normal distribution. The purification process removed almost all nanowires with a diameter of 15 nm or less. Furthermore, purified nanowires have less spread or variation around the average diameter.

(Example 3)
Measurement of Length Distribution Three batches of silver nanowires were prepared and purified according to Examples 1 and 2. Nanowire samples were randomly collected from each batch. The nanowire length of each sample was measured and analyzed using an optical microscope and Cremex software as described herein. Table 1 shows the size distribution of nanowires prepared in 3 batches.

さらに、図５は、３バッチの銀ナノワイヤのサイズ分布プロファイルを対数正規分布として示す。再現性のあるサイズ分布プロファイルが、本明細書に記載の合成及び精製プロセスに従って調製されたナノワイヤにおいて得られたことが実証された。

Further, FIG. 5 shows the size distribution profile of three batches of silver nanowires as a lognormal distribution. It has been demonstrated that a reproducible size distribution profile was obtained in nanowires prepared according to the synthesis and purification processes described herein.

  Length statistics are summarized in Table 2.

（実施例４）
直径分布の測定
ナノワイヤ試料を各バッチから無作為に収集して、その直径分布を測定した。各試料のナノワイヤ幅を、本明細書に記載のように、ＳＥＭ及びＣｌｅｍｅｘソフトウェアを使用して測定し、分析した。表３は、３つの異なるバッチで調製されたナノワイヤの直径分布を示す。

(Example 4)
Measurement of Diameter Distribution Nanowire samples were randomly collected from each batch and their diameter distribution was measured. The nanowire width of each sample was measured and analyzed using SEM and Cremex software as described herein. Table 3 shows the diameter distribution of nanowires prepared in three different batches.

さらに、図６は、３バッチの銀ナノワイヤの直径分布プロファイルを正規分布、すなわちガウス分布として示す。再現性のある直径分布プロファイルが、本明細書に記載の合成及び精製プロセスに従って調製されたナノワイヤにおいて得られたことが実証された。

Furthermore, FIG. 6 shows the diameter distribution profile of three batches of silver nanowires as a normal distribution, ie a Gaussian distribution. It was demonstrated that a reproducible diameter distribution profile was obtained in nanowires prepared according to the synthesis and purification processes described herein.

  Diameter statistics including standard deviations are summarized in Table 4.

（実施例５）
透明導体の調製
実施例１及び２によって調製された銀ナノワイヤの各バッチから、重量で、０．１〜０．２％銀ナノワイヤ、０．２〜０．４％高純度ＨＰＭＣ、及び０．００５〜０．０２５％Ｔｒｉｔｏｎ Ｘ−１００のＤＩ水溶液を含むようにインク組成物を製剤化した。次いで、インク組成物をガラス基体にスピンコートして薄膜を形成した。より具体的には、試料を速度４００から２０００ｒｐｍで６０秒、加速度１０００ｒｐｍ／ｓでスピンコートした。続いて、膜を５０℃で９０秒、続いて１４０℃で９０秒焼付けした。

(Example 5)
Transparent Conductor Preparation From each batch of silver nanowires prepared according to Examples 1 and 2, 0.1 to 0.2% silver nanowires, 0.2 to 0.4% high purity HPMC, and 0.005 by weight. The ink composition was formulated to contain a 0.025% Triton X-100 DI aqueous solution. Next, the ink composition was spin coated on a glass substrate to form a thin film. More specifically, the sample was spin coated at a speed of 400 to 2000 rpm for 60 seconds and an acceleration of 1000 rpm / s. Subsequently, the membrane was baked at 50 ° C. for 90 seconds, followed by 140 ° C. for 90 seconds.

  A series of thin films based on each batch of ink composition were prepared by adjusting the loading, rotational speed and time.

(Example 6)
Transparent Conductor Specifications The resistance, transmittance and haze data for each batch of thin film are summarized in Tables 5-7. The haze and transmittance (0.04% H and transmittance 93.4%) of the bare glass were not subtracted.

膜はすべて曇価が１．５％未満であり、高い透過率及び導電率を維持した。特に、曇価０．４％未満及び抵抗３５０オーム／ｓｑ未満の膜が得られた。

All films had a haze value of less than 1.5% and maintained high transmission and conductivity. In particular, a film having a haze value of less than 0.4% and a resistance of less than 350 ohm / sq was obtained.

  Furthermore, FIG. 7 shows an inverse correlation between the haze value and resistance of the thin film. It can be seen that as the resistance increases (ie, in the presence of fewer nanowires), the haze value decreases due to the reduced scattering.

  FIG. 8 shows a positive correlation between the transmittance of the thin film and the resistance. It can be seen that the transmission increases as the resistance increases (ie, there are fewer nanowires).

(Example 7)
Evaluation of optical and electrical properties of transparent conductors Transparent conductive films prepared by the methods described herein were evaluated to determine their optical and electrical properties.

  Light transmittance data was obtained by the method of ASTM D1003. The haze was measured using a BYK Gardner Haze-gard Plus. Sheet resistance was measured using a Fluke 175 True RMS Multimeter or a non-contact ohmmeter Delcom model 717B conductance monitor. A more typical device is a four-point probe system for resistance measurement (eg, by Keithley Instruments).

  The haze and transmittance of the bare substrate (eg, for glass, haze of 0.04% and transmittance of 93.4%) were typically included in the measurements.

  The interconnectivity of the nanowires and the area ratio of the substrate can also be observed under an optical or scanning electron microscope.

  All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referenced herein and / or listed in the application data sheet. This is incorporated herein.

From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Let's go. Accordingly, the invention is not limited except as by the appended claims.
According to a preferred embodiment of the present invention, for example, the following is provided.
(Claim 1)
A transparent conductor comprising a plurality of conductive nanostructures, wherein the transparent conductor has a haze value of less than 1.5%, a light transmittance of greater than 90%, and a sheet resistance of less than 350 ohms / square; Transparent conductor.
(Section 2)
Item 2. The transparent conductor according to Item 1, wherein the sheet resistance is less than 50 ohm / square.
(Section 3)
Item 2. The transparent conductor according to Item 1, wherein the haze value is less than 0.5%.
(Claim 4)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 99% of the conductive nanostructure having an aspect ratio of at least 10 has a length of 55 μm or less.
(Section 5)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 99% of the conductive nanostructure having an aspect ratio of at least 10 has a length of 45 μm or less.
(Claim 6)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 have a length of about 5 to 50 μm.
(Claim 7)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 95% of the conductive nanostructure having an aspect ratio of at least 10 has a length of about 5 to 30 μm.
(Section 8)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average length of about 10 to 22 μm.
(Claim 9)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average square length of about 120 to 400 µm ² .
(Section 10)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 99% of the conductive nanostructure having an aspect ratio of at least 10 has a diameter of 55 nm or less.
(Item 11)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 99% of the conductive nanostructure having an aspect ratio of at least 10 has a diameter of 45 nm or less.
(Clause 12)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of about 15 to 50 nm.
(Section 13)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of about 20 to 40 nm.
(Item 14)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 26 to 32 nm and a standard deviation in the range of 4 to 6 nm.
(Section 15)
Item 4. The transparent conductor according to any one of Items 1 to 3, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 29 nm and a standard deviation in the range of 4 to 5 nm.
(Section 16)
More than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a length of 55 μm or less, and more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 55 nm or less. Item 4. The transparent conductor according to any one of Items 1 to 3.
(Section 17)
More than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 50 μm in length, and more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 15 to 50 nm in diameter. The transparent conductor according to any one of Items 1 to 3, wherein:
(Item 18)
More than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 30 μm in length, and more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 20 to 40 nm in diameter. The transparent conductor according to any one of Items 1 to 3, wherein:
(Section 19)
The conductive nanostructure having an aspect ratio of at least 10 has an average length of about 10 to 22 μm, the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 26 to 32 nm, Item 4. The transparent conductor according to any one of Items 1 to 3, wherein the deviation is in the range of 4 to 6 nm.
(Section 20)
More than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a length of 45 μm or less, and more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 45 nm or less. Item 4. The transparent conductor according to any one of Items 1 to 3.
(Item 21)
A method comprising a step of growing metal nanowires from a reaction solution containing a metal salt and a reducing agent, the growing step comprising:
Reacting the metal salt in the reaction solution with a first portion of the reducing agent for a first time; and having a substantially constant concentration of less than 0.1% w / w of the metal salt in the reaction solution. Gradually adding the second portion of the metal salt over a second time while maintaining.
(Item 22)
Item 22. The method according to Item 21, wherein the metal nanowire is a silver nanowire, the metal salt is silver nitrate, and the reducing agent is propylene glycol or ethylene glycol.
(Item 23)
Reacting the metal salt in the reaction solution with the first half of the reducing agent for the first time,
Item 22. The method of Item 21, comprising adding a portion of the first portion of the metal salt together with an ammonium salt and adding the remainder of the first portion of the metal salt.
(Section 24)
A plurality of the conductive nanostructures, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a length of 55 μm or less;
A viscosity modifier;
A surfactant,
An ink composition comprising a dispersion fluid.
(Claim 25)
Item 25. The ink composition according to Item 24, wherein more than 99% of the conductive nanostructure having an aspect ratio of at least 10 is 45 μm or less in length.
(Section 26)
Item 25. The ink composition of Item 24, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 50 μm in length.
(Claim 27)
27. The ink composition of item 26, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 30 μm in length.
(Item 28)
25. The ink composition according to item 24, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average length of about 10 to 22 μm.
(Item 29)
25. The ink composition according to item 24, wherein an average square length of the conductive nanostructure having an aspect ratio of at least 10 is about 120 to 400 μm ² .
(Section 30)
A plurality of the conductive nanostructures, wherein more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 55 nm or less;
A viscosity modifier;
A surfactant,
An ink composition comprising a dispersion fluid.
(Claim 31)
Item 31. The ink composition according to Item 30, wherein more than 99% of the conductive nanostructure having an aspect ratio of at least 10 has a diameter of 45 nm or less.
(Item 32)
Item 31. The ink composition of Item 30, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of about 15 to 50 nm.
(Paragraph 33)
Item 31. The ink composition according to Item 30, wherein more than 95% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of about 20 to 40 nm.
(Item 34)
Item 31. The ink composition according to Item 30, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 26 to 32 nm and a standard deviation in the range of 4 to 6 nm.
(Claim 35)
The ink composition according to item 30, wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 29 nm and a standard deviation in the range of 4 to 5 nm.
(Claim 36)
A plurality of conductive nanostructures;
A viscosity modifier;
A surfactant,
An ink composition comprising a dispersion fluid,
More than 99% of the conductive nanostructures with an aspect ratio of at least 10 have a length of 55 μm or less, and more than 99% of the conductive nanostructures with an aspect ratio of at least 10 have a diameter of 55 nm or less Composition.
(Paragraph 37)
More than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 50 μm in length, and more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 15 to 50 nm in diameter. Item 37. The ink composition according to Item 36, wherein
(Claim 38)
More than 95% of the conductive nanostructures having an aspect ratio of at least 10 are about 5 to 30 μm in length, and more than 95% of the conductive nanostructures having an aspect ratio of at least 10 are from about 20 in length. Item 37. The ink composition according to Item 36, wherein the ink composition is 40 nm.
(Item 39)
The conductive nanostructure having an aspect ratio of at least 10 has an average length of about 10 to 22 μm, the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of about 26 to 32 nm, Item 37. The ink composition according to Item 36, wherein the deviation is in the range of 4 to 6 nm.
(Claim 40)
More than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a length of 45 μm or less, and more than 99% of the conductive nanostructures having an aspect ratio of at least 10 have a diameter of 45 nm or less. Item 37. The ink composition according to item 36.

Claims (13)

A method comprising a step of growing metal nanowires from a reaction solution containing a metal salt and a reducing agent, the growing step comprising:
Reacting a first portion of the metal salt in the reaction solution with the reducing agent for a first time; and a substantially constant concentration of the metal salt in the reaction solution of less than 0.1% w / w. Gradually adding a second portion of the metal salt over a second time while maintaining,
Reacting the first portion of the metal salt in the reaction solution with the reducing agent for the first time,
Adding a portion of the first portion of the metal salt together with an ammonium salt, and adding the remainder of the first portion of the metal salt.   The method according to claim 1, wherein the metal nanowire is a silver nanowire, the metal salt is silver nitrate, and the reducing agent is propylene glycol or ethylene glycol. Aspect ratio 9 9% of conductive nanostructures is at least 10 (number basis) of diameter 55nm or less, and the plurality of conductive nanostructures,
A viscosity modifier;
A surfactant,
A dispersion fluid,
Aspect ratio conductive nanostructures less than 10, less than one 0% conductive nanostructures in the ink composition (number basis), the ink composition. Aspect ratio 9 9% of the conductive nanostructures is at least 10 (number basis) is less than the diameter 45 nm, the ink composition according to claim 3. Aspect ratio 95% greater than the conductive nanostructures is at least 10 (number basis) is 50nm in diameter 15, the ink composition according to claim 3. The aspect ratio of at least 10 95% than the conductive nanostructures (number basis) is 40nm in diameter 20, the ink composition according to claim 3. The ink composition according to claim 3 , wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of 26 to 32 nm and a standard deviation of 4 to 6 nm. The ink composition according to claim 3 , wherein the conductive nanostructure having an aspect ratio of at least 10 has an average diameter of 29 nm and a standard deviation in the range of 4 to 5 nm. A plurality of conductive nanostructures;
A viscosity modifier;
A surfactant,
An ink composition comprising a dispersion fluid,
Aspect ratio 9 9% of the conductive nanostructures is at least 10 (number basis) or less in length 55 .mu.m, 99% more than (the number of the conductive nanostructures aspect ratio of at least 10 The standard) is 55 nm or less in diameter,
Aspect ratio conductive nanostructures less than 10, less than one 0% conductive nanostructures in the ink composition (number basis), the ink composition. The aspect ratio of at least 10 9 5% of the conductive nanostructures (number basis) of 50μm the length 5, 9 5% of the conductive nanostructures aspect ratio of at least 10 ( The ink composition according to claim 9, wherein the number basis is 15 to 50 nm in diameter. The aspect ratio of at least 10 9 5% of the conductive nanostructures (number basis) of 30μm the length 5, 9 5% of the conductive nanostructures aspect ratio of at least 10 ( The ink composition according to claim 9 , wherein the number basis is 20 to 40 nm in length. The average length of the conductive nanostructure having an aspect ratio of at least 10 is 10 to 22 μm, the average diameter of the conductive nanostructure having an aspect ratio of at least 10 is 26 to 32 nm, and the standard deviation is The ink composition according to claim 9 , which is in the range of 4 to 6 nm. Aspect ratio 9 9% of the conductive nanostructures is at least 10 (number basis) is at 45μm or less in length, 9 9 percent (the number of the conductive nanostructures aspect ratio of at least 10 The ink composition according to claim 9 , wherein the standard is a diameter of 45 nm or less.

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